Camera for vehicle vision system

ABSTRACT

A vehicular camera includes a lens, a printed circuit board and an imager. The lens has a plurality of optical element and is disposed at a lens holder. The imager is disposed at the printed circuit board. The adhesive is initially curable in an initial radiation curing process that comprises exposure to UV light, and initially-cured adhesive is further curable to a further cured strength in a secondary thermal curing process. The adhesive is initially cured via the initial radiation curing process after the lens is brought into focus with the imager and is optically center-aligned therewith. The initially-cured adhesive, as cured via the initial radiation curing process, holds the lens optically center-aligned and in focus with the imager. After the initial radiation curing process, the lens holder, adhesively attached to one of the printed circuit board and the holding element, is moved to the secondary thermal curing process.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims the filing benefits of U.S. provisionalapplication Ser. No. 61/905,462, filed Nov. 18, 2013 and Ser. No.61/901,127, filed Nov. 7, 2013, which are hereby incorporated herein byreference in their entireties.

FIELD OF THE INVENTION

The present invention relates generally to vehicle vision systems and,more particularly, to vehicular cameras for vehicle vision systems.

BACKGROUND OF THE INVENTION

Vehicular cameras are used for a variety of purposes, such as to assista driver in avoiding obstacles behind a vehicle when backing up, and todetect imminent collisions ahead of the vehicle when driving forward. Avehicular camera includes a lens that focuses video input on an imagesensor provided on an imager. In general, the position of the lensrelative to the image sensor can impact the quality of the video inputreceived by the image sensor. For example, if the lens is positionedsuch that the video input is not in focus, then the video informationpassed to the driver may be blurry, and other vehicular systems, such asa collision detection system for example, may not function as well asthey otherwise could. As the size of the camera is reduced, thepositioning of the lens relative to the image sensor may be relativelymore critical, at least because small variations in position can resultin relatively large changes in angular offset. Therefore, thepositioning of the lens relative to the image sensor may be particularlycritical for vehicular rearview cameras. Furthermore, it is importantthat the camera be capable of holding the lens in position over aselected period of time under certain operating conditions, so that theperformance of the camera is maintained over a useful operating life.

Several aspects of the camera may contribute to the overall tolerance inthe position of the lens relative to the image sensor. For example, forlenses and lens holders that are threaded, the threaded connectiontherebetween has a tolerance associated with it. The angle of cast ofthe lens holder has a tolerance associated with it. The position of theimager has a tolerance associated with it.

It is desirable to provide a more integrated, lower cost camera assemblywith means for positioning the lens relative to the imager withintolerance.

SUMMARY OF THE INVENTION

The present invention provides a vehicular camera assembly having a lensand imager, and with the lens focused at the imager and adhered relativeto the imager using an adhesive that provides enhanced bond strength andstability, and that is resistant to environmental aging. The adhesive isinitially curable in an initial curing process that comprises exposureto UV light, and the initially-cured adhesive is further curable to afurther cured strength in a secondary curing process.

The adhesive comprises a UV curable and heat curable one-part filledadhesive having a viscosity at 23 degrees C. from about 5,000 mPa toabout 150,000 mPa and comprising an epoxy resin. The preferred adhesiveis adhesive OB749 or AD VE 112203 or OB787, manufactured by DeloIndustrial Adhesives of Sudbury, Mass. and Windach, Germany. Suchadhesives are UV-/light-/heat curing adhesives having medium viscosity.

These and other objects, advantages, purposes and features of thepresent invention will become apparent upon review of the followingspecification in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a vehicle with a vision system thatincorporates cameras in accordance with the present invention;

FIG. 2 is an exploded perspective view of a vehicular camera inaccordance with an first embodiment of the invention wherein a lensbarrel is adhesively secured to a lens holder via a UV-curable adhesive;

FIG. 3 is a cutaway side view of the vehicular camera shown in FIG. 2,in an assembled state;

FIG. 4 is a camera of the present invention, which is assembled by thelens assembly being held in a fixed position while the imager printedcircuit board or PCB (with the image sensor) is positioned relative tothe lens assembly;

FIG. 5 is a camera of the present invention, which is assembled by theimager PCB being held in a fixed position while the lens is positionedrelative to the PCB;

FIG. 6 is an exploded view of a camera assembly that is assembled withan adhesive in accordance with the present invention;

FIG. 7 is an end view of the camera assembly of FIG. 6;

FIG. 7A is a sectional view of the camera assembly taken along the lineA-A in FIG. 7;

FIG. 8 is a graph showing the movement of the lens relative to theimager after testing for various camera assemblies;

FIG. 9 shows test results of an exemplary production adhesive; and

FIG. 10 shows test results of the preferred adhesive for the cameraassembly of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

A vehicle vision system and/or driver assist system and/or objectdetection system and/or alert system operates to capture images exteriorof the vehicle and may process the captured image data to display imagesand to detect objects at or near the vehicle and in the predicted pathof the vehicle, such as to assist a driver of the vehicle in maneuveringthe vehicle in a rearward direction. The vision system includes an imageprocessor or image processing system that is operable to receive imagedata from one or more cameras and provide an output to a display devicefor displaying images representative of the captured image data.Optionally, the vision system may provide a top down or bird's eye orsurround view display and may provide a displayed image that isrepresentative of the subject vehicle, and optionally with the displayedimage being customized to at least partially correspond to the actualsubject vehicle.

Referring now to the drawings and the illustrative embodiments depictedtherein, a vehicle 2 includes an imaging system or vision system 4 thatincludes at least one exterior facing imaging sensor or camera 10, suchas a rearward facing imaging sensor or camera 10 a (and the system mayoptionally include multiple exterior facing imaging sensors or cameras,such as a forwardly facing camera 10 b at the front (or at thewindshield) of the vehicle, and a sidewardly/rearwardly facing camera 10c, 10 d at respective sides of the vehicle), which captures imagesexterior of the vehicle, with the camera having a lens for focusingimages at or onto an imaging array or imaging plane or imager of thecamera (FIG. 1). The vision system 4 includes a control or electroniccontrol unit (ECU) or processor 6 that is operable to process image datacaptured by the cameras and may provide displayed images at a displaydevice 8 for viewing by the driver of the vehicle (although shown inFIG. 1 as being part of or incorporated in or at an interior rearviewmirror assembly 9 of the vehicle, the control and/or the display devicemay be disposed elsewhere at or in the vehicle). The data transfer orsignal communication from the camera to the ECU may comprise anysuitable data or communication link, such as a vehicle network bus orthe like of the equipped vehicle.

FIG. 2 shows an exploded view of an exemplary vehicular cameraconstruction 10, which may be assembled in accordance with the presentinvention. The vehicular camera 10 includes an imager 20, a lens holdersuch as a front camera housing 14 and a lens 16. The vehicular camera 10may include other components such as additional circuitry for processingthe video input received by the imager 20, such as, for example,circuitry for providing graphic overlay to the video input or the like.The vehicular camera 10 may further be configured to transmit the videoinput to other vehicular devices, such as a display controller (notshown) for a cabin-mounted display (not shown).

The imager 20 may be a charge-coupled device (CCD) or a complimentarymetal-oxide semiconductor (CMOS) sensor. Referring additionally to FIG.3, the imager 20 is mounted to a printed circuit board (PCB) 12. Theimager 20 is positioned to receive optical images from the lens 16.Optionally, and such as shown in FIGS. 2 and 3, the imager 20 may beconnected to the lens holder 14 by a plurality of threaded fasteners 22.

The lens 16 is mounted to the lens holder/front camera housing 14 at aselected position for focusing images onto the sensing surface of theimager 20. The lens 16 may comprise any suitable type of lens known inthe art and may comprise multiple glass or plastic lens optics orelements disposed in and along a lens barrel. In the illustratedembodiment, the lens 16 has an exterior surface 24 that is configured tobe received in a cylindrical aperture 26 having an aperture wall 28 onthe lens holder/front camera housing 14. The exterior surface 24 and theaperture wall 28 may have a selected amount of clearance therebetween,shown by a gap G. An adhesive 30 is provided for holding the lens 12 ina specific position relative to the lens holder/front camera housing 14.More particularly, the adhesive 30 may be applied between a first axialface 32 on the lens holder/front camera housing 14, and a second axialface 34 on the lens 16.

The position of the lens 16 relative to the imager 20 impacts the degreeof focus present in the optical images received by the imager 20 andthus the performance of the camera 10 and the optical alignment of theoptical image on the imager.

To control the position of the lens 16, a positioning system may beprovided that includes a robot. The robot holds and adjusts the positionof the lens 16 relative to the lens holder/front camera housing 14 untila target object appears in suitable focus and at a suitable position onthe imager 20, prior to the curing or hardening of the adhesive 30. Theadjustment of the lens 16 relative to the lens holder/front camerahousing 14 is facilitated by providing the selected amount of clearancebetween the exterior surface 24 of the lens 16 and the aperture wall 28of the lens holder/front camera housing 14. Additionally, the thicknessof the layer of adhesive 30 between the lens 16 and lens holder/frontcamera housing 14 may be selected to provide a suitable amount ofrelative angular adjustment between the lens 16 and lens holder 14/frontcamera housing. The thickness of the layer of adhesive may beapproximately 0.75 mm prior to adjustment of the lens 16.

Once the lens 16 has been suitably positioned by the robot, the adhesive30 is initially cured by exposure to UV light while the robot holds thelens 16 in position. The UV light may be provided from a plurality of UVsources about the periphery of the camera 10. The initial curing of theadhesive 30 may result in the adhesive being strong enough to hold thelens 16 in the lens holder/front camera housing 14 without needing therobot to grip the lens 16, and may take less than about 10 seconds, suchas less than about 7 seconds. However, the lens 16 may be susceptible tomovement if it incurs a relatively small disturbance at this stage.After the initial curing, the camera 10 may be placed by the robotrelatively gently on a conveyor and moved to a further curing station,such as a further UV curing station for a further UV curing period, suchas, for example, about 25 seconds. Another curing station, such asanother UV curing station may optionally be provided to further cure theadhesive 30 for another period, such as about 25 seconds, after thecamera 10 leaves the first UV curing station. Subsequent to the UVcuring, the camera 10 may be transferred to another curing station wherethe adhesive 30 can be thermally cured, or may be cured by exposure tosome other secondary curing condition, to achieve its fully curedstrength so that it can hold the lens 16 in position during use on avehicle. The step of initially curing the adhesive 30 using UV light maybe relatively instantaneous. The step of thermally curing the adhesivemay take several minutes or hours. As an additional or alternativecuring measure, the adhesive 30 may be moisture cured.

Providing an adhesive 30 that has an initial curability by UV light isadvantageous in that the robot is not needed to hold the lens 16 inposition over the period of time that it would take for the secondarycuring condition to sufficiently harden the adhesive 30 to beself-supporting. Once the camera 10 is transferred from the robot to thecuring fixture, the robot can be used for the positioning of anotherlens 16 in another lens holder 14/front camera housing. Because the taskof positioning the lens 16 and initially curing the adhesive 30 using UVlight can take less time than fully thermally curing of the adhesive 30,a single robot can feed cameras 10 with initially cured lenses to aplurality of curing fixtures, thereby providing the capability ofachieving a relatively high rate of production per robot.

Once fully cured, the adhesive 30 may be capable of holding the lens 16in position with at least a selected strength of bond between the lens16 and lens holder/front camera housing 14 under one or more selectedoperating conditions. For example, the adhesive 30 may be capable ofholding the lens 16 in position after a selected time period of 1000hours of exposure to a selected temperature of about 85 degrees Celsiusand optionally a humidity of approximately 85%. Any of theaforementioned selected values may be selected to suit the particularenvironment that the camera 10 is expected to experience during use. Theselected time period may, for example, be some other time period, suchas approximately 1200 hours. The selected adhesive 30 may be furthercapable of holding the lens 16 in position after a selected time periodexposed to a selected temperature of about −40 degrees Celsius.

The adhesive 30 may be applied by the robot itself prior to adjustmentof the lens 16 relative to the lens holder/front camera housing 14(where the lens is brought into focus with the imager and is opticallycenter-aligned therewith). Alternatively, the adhesive 30 may be appliedby some other device prior to (or during) possession of the camera 10 bythe robot.

Optionally, and aside from fixing the position of the lens 16 relativeto the lens holder/front camera housing 14, the adhesive 30 may alsohermetically seal the interior of the camera 10 against the outsideenvironment.

Numerous adhesives were attempted for use as the adhesive 30. Forexample, it was found that some adhesives, such as some UV-cure freeradical acrylates that have the capability of being initially curedusing UV light, have a reduced strength (such as a reduced tensilestrength) under exposure to elevated operating temperatures such asabout 85 degrees Celsius over a selected period of time. It was furtherfound that adhesives, such as some UV-curable free radical epoxy hybridsalso have a reduced strength (such as a reduced tensile strength) underexposure to elevated operating temperatures such as about 85 degreesCelsius over a selected period of time. Some anionic cyanoacrylates thatwere tried were unsuitable as they produced too much outgas for opticaluse. Other adhesives, such as some UV-cure free radical silicones or thelike, have a relatively low dimensional stability and are thus notsuitable.

It has been found that a suitable adhesive that can be used for theadhesive is adhesive AD VE 43812 manufactured by Delo IndustrialAdhesives of Windach, Germany. This adhesive is a low-temperature cure,epoxy-amine adhesive that can be cured initially relatively quickly byexposure UV light. Aspects of this adhesive are suitable for use in avehicular camera, such as described in U.S. Pat. No. 8,542,451 and/orInternational Publication No. WO 2013/063014, which are herebyincorporated herein by reference in their entireties.

Automotive cameras are assembled by way of a precise spatial positioningof the image sensor relative to the lens. This may be achieved in twoways. For a camera of the type shown in FIG. 4, the lens assembly isheld in a fixed position while the imager printed circuit board or PCB(with image sensor) is positioned relative to the lens assembly (such asvia a robot that moves the PCB relative to the lens assembly, which isheld or fixed at a fixture). For a camera of the type shown in FIG. 5,the imager PCB is held in a fixed position (such as via a fixture) whilethe lens is positioned (such as via a robot) relative to the fixturedPCB (such as by utilizing aspects of the systems described inInternational Publication No. WO 2013/063014, which is herebyincorporated herein by reference in its entirety). The camera may havethe lens threadedly attached at the lens holder and threadedlyadjustable to adjust the focus of the images at the imager. Optionally,the lens barrel may threadedly attach at the lens holder, or the lensbarrel may adhesively attach at the lens holder, or the lens barrel maythreadedly and adhesively attach at the lens holder. Optionally, thelens barrel may be unitarily formed with or integrated into the lensholder such that they comprise a single or unitary element or piece ofunitary construction.

For either type of cameras, a compliant connecting member or elementmust exist between the two components that allows for the relativemovement or adjustment of the lens relative to the imager (to bring thelens into focus with the imager and to optically center-align the lenswith the imager). This connecting member or bonding material or elementmust also have a means of being permanently fixed once the desiredposition is found. A UV curable adhesive, such as described in U.S. Pat.No. 8,542,451 and/or International Publication No. WO 2013/063014, whichare hereby incorporated herein by reference in their entireties, may beused for this member.

FIGS. 6, 7 and 7A show views of another exemplary vehicular cameraconstruction 110, which may be assembled in accordance with the presentinvention. The vehicular camera 110 includes an imager 120 disposed at aprinted circuit board or PCB 112, a lens holder 114 and a lens 116. Thevehicular camera 110 may include other components such as additionalcircuitry for processing the video input received by the imager 120,such as, for example, circuitry for providing graphic overlay to thevideo input or the like. The vehicular camera 110 may further beconfigured to transmit the video input to other vehicular devices, suchas a display controller (not shown) for a cabin-mounted display (notshown). As shown in FIG. 6, the adhesive 130 may be disposed between thelens 116 and the lens holder 114, which is attached at the printedcircuit board 112 via a plurality of fasteners or screws 136.

The front camera module (FCM) of the present invention is designed withthe intent to maintain highest focus possible throughout the life andusage of the camera. The focus is found during the assembly process(such as during an assembly process of the type described in U.S. Pat.No. 8,542,451 and/or International Publication No. WO 2013/063014, whichare hereby incorporated herein by reference in their entireties), and ismaintained over the life of the part. This effective focal length (EFL)may have a minimum tolerance of about +/−0.02 mm (+/−20μ).

In order to be suitable for use on a vehicle over the lifetime of thevehicle, the FCM must meet the ECE-R48 government regulation forautomatic high-beam control (AHBA) functions. AHBA must be capable todetect an oncoming vehicle, and shutdown the high-beam/revert back tolow-beam while the oncoming vehicle is greater than 400 m distance fromthe subject or equipped or host vehicle. The required distance has beencorrelated to a focus score threshold for the Camera. This focusthreshold is determined by testing done by both the FCM manufacturer andthe vehicle manufacturer and is 40 line pairs/mm (MTF). This focusthreshold must be maintained for the life of the camera, fromend-of-line build confirmation focus score to up to ten years of servicein the field.

The focus requirement is shown in FIG. 8. The graph of FIG. 8 showstypical through-focus curves for the lenses used on the forward facingcamera module (FCM). The challenge is to build at a specification thatprovides an optimized optical zone, such as to build at about 40 MTF,and to maintain that focus over time. Note that typical capability toachieve this performance resides in a narrow distance of, for example,about 47μ. Thus, the FCM imager assembly, once built, cannot move morethan, for example, about 0.040 mm or so, over its lifetime of use on avehicle. This includes its life and use during heat exposure, duringthermal expansion during normal operation, during exposure to humidityand/or the like, and includes manufacturing tolerances and variations.

FIG. 8 shows test results for the adhesive of the present invention ascompared to other exemplary proposed production intent adhesives. Basedon validation to environments requirements (such as maintaining focusgreater than 40 MTF after exposure to (i) high temperature degradation(400 hours at 90 degrees C.) and (ii) humidity (240 hours at 85 degreesC. and 90% relative humidity)), the graph shows that the other exemplaryadhesive has a total movement of approximately −35μ to +45μ, whichresults in about +80μ total movement, which is much greater than theminimum lens capability (such as, for example, about +40μ). As shown inFIG. 8, the adhesive of the present invention has a total movement ofapproximately −18μ to +18μ, which results in about +36μ total movement,which is less than the minimum lens capability, and thus meets thedesired performance. FIGS. 9 and 10 show further test results of anexemplary production adhesive (FIG. 9) and the adhesive as applied inaccordance with the present invention (FIG. 10).

Thus, the present invention provides an improved adhesive that providesenhanced performance and strength of the bond that holds the lensrelative to the imager. The adhesive was selected based on many of itsproperties—dimensional stability, resistance to environmentalconditioning, quick cure time, bond strength, dual cure nature, and thelike. Requirements for improved focus for high resolution mega pixelcameras and forward facing machine vision systems have led to requestsfor such an enhanced adhesive. It has been found that a higher bondstrength is desired to better support global manufacturing processes inwhich cure parameters (which effect adhesive properties and bondstrength) may vary. In summary, improved dimensional stability and bondstrength have been seen as desirable characteristics of the selectedadhesive.

In general and as previously stated, the present invention provides anadhesive for a vehicular camera that has a high bond strength andexcellent dimensional stability, and that is resistant to environmentalaging and is UV curable with secondary cure mechanism. The below list isa summary of expectations:

-   -   −40 degrees C. to 105 degrees C. operating range while        maintaining greater than about 70 percent strength    -   Tensile strength greater than 700 PSI    -   Greater than about 50 Shore D hardness    -   30 k to 70 k cp viscosity    -   UV Curable fixture in less than about 7 seconds    -   Fully Curable in about 30 seconds or more    -   Secondary two-part, moisture or thermal    -   Non-hygroscopic (no significant moisture swell)    -   Cure depth greater than about 3 mm    -   Bond to PBT/PC and PBT plastics, FR4 PCB's, zinc and aluminum.    -   Bond Shear Strength greater than about 1000 PSI with less than        about 60 percent reduction at about 85 degrees C.    -   Very little to no out gassing    -   Withstand 1210 hours at about 85 degrees C./85% humidity    -   Automotive grade    -   Glass Transition Temperature greater than about 90 degrees C.

The below lists shows how the adhesive of the present invention hasimproved properties in comparison to the currently used product

-   -   Higher Tg (95 degrees C. vs. 86 degrees C.)    -   Less Thermal expansion (44-113 vs. 152-190)    -   Less shrinkage (2.2% vs. 3.25%)    -   Less water absorption (0.1% vs. 0.3%)    -   Tensile strength greater than 5 times other adhesive (41 MPa vs.        7 MPa)        Improvements Achieved and how this Impacts Product Performance:

The adhesive of the present invention outperforms current adhesives inmany ways or every way that is of importance to the performance anddurability of the vehicular camera:

-   -   Bond strength is nearly twice as strong as what is seen in        previous adhesives.        -   Limits or avoids risk of bond break failures and makes the            process much less sensitive to cure parameter precision.    -   Cure time is much faster which reduces cycle time.        -   Limits or avoids risk of bond failures and makes the process            more robust by making it much less sensitive precise cure            parameter.    -   Shrink after cure is nearly non-existent.        -   The previous adhesive continues to shrink some after the            product is built since the adhesive is not considered to be            fully cured until 48 hours after UV and thermal cure. The            processes must offset the focus position in anticipation of            such shrinkage.    -   Dimensional change from moisture absorption is nearly        non-existent.

Testing of the adhesive of the present invention has shown that thebonded components bonded together using the adhesive of the presentinvention have retention forces of twice (or more) that of other testedadhesives, such as in tests where the bonded components are first storedat room temperature for approximately 30 days, or where the bondedcomponents are thermally shocked via 10 days of cycling the partsbetween −40 degrees C. and 100 degrees C., or where the bondedcomponents are first thermally shocked for ten days and then soaked forten days at 85 degrees C. at 85% relative humidity.

The adhesive comprises a UV curable adhesive that preferably is aone-part, solvent free, filled adhesive comprising a modified epoxyresin. Such adhesives, as well as being UV curable, can also be curedthermally, such as by heat. For example, the adhesive preferablycomprises an OB749 adhesive or AD VE 112203 or OB787 adhesive, bothmanufactured by Delo Industrial Adhesives of Sudbury, Mass. and Windach,Germany. Such adhesives are UV-/light-/heat curing adhesives havingmedium viscosity. Preferably, such UV light/heat curing adhesives have aviscosity in the range from about 5,000 mPa to about 150,000 mPa,preferably from about 10,000 mPa to 130,000 mPa, more preferably fromabout 12,000 mPa to about 120,000 mPa. Thus, the adhesive of the cameraof the present invention comprises a UV curable and heat curableone-part filled adhesive having a viscosity at 23 degrees C. from about5,000 mPa to about 150,000 mPa and comprising an epoxy resin. The AD VE112203 or OB787 adhesive is substantially similar to the OB749 adhesive,but has a filler added to provide a preferred viscosity of the uncuredadhesive. For example, the OB749 adhesive has a viscosity (at 23 degreesC.) of about 14,000 mPa, while the AD VE 112203 or OB787 adhesive has aviscosity (at 23 degrees C.) of about 115,000 mPa.

DELO®.DUALBOND® AD VE 112203 (a trade mark of and available from DELOIndustrial Adhesives LLC of Sudbury, Mass.) or OB787 (the commercialproduct of the AD VE 112203 engineering development adhesive) comprisesa UV-/light-/heat curing adhesive, medium viscosity, base modified epoxyresin, one-part, solvent free, filled, UV-/light-/heat curing adhesiveformulated especially for fast fixing of components with high strengthafter irradiation and suitable for the bonding of metal, glass, plasticand other materials as well as for the coating, fixing or sealing ofelectronic components. It is normally used in a temperature range of −40degrees C. to +150 degrees C., depending on the application. Thisadhesive is compliant with RoHS directive 2011/65/EU and is halogen-freeaccording to IEC 61249-2-21. Curing of this adhesive is achieved with UVlight or visible light, preferably in a wavelength range of about 320 nmto about 440 nm, or with heat. The light-curing mechanism and theheat-curing mechanism can be used independently. The color (cured in alayer thickness of approximate 0.1 mm) is white. The viscosity [mPa] at23 degrees C., Brookfield rpm 7/5 is 115,000. The composition ofDELO®DUALBOND® AD VE 112203 or OB787 comprises vitreous Silica [CAS No.60676-86-0 and %25-75], reaction product bisphenol-A-(epichlorhydrin);epoxy resin [CAS No. 25068-38-6 and %10-25], and Quartz (SiO₂) [CAS No.14808-60-7 and %<2.5], and includes 7-oxabicyclo [4.1.0]hept-3-ylmethyl7-oxabicyclo [4.1.0]heptane-3-carboxylate reaction product;bisphenol-A-(epichlorhydrin); epoxy resin.

Therefore, the present invention provides a camera assembly thatutilizes such an adhesive to bond the lens relative to the imager orPCB. The vehicular camera comprises (i) a lens having a plurality ofoptical elements and disposed at a lens holder, (ii) a printed circuitboard and (iii) an imager disposed at said printed circuit board. Theprinted circuit board may be held by a holding element and the lensholder may be attached at the holding element by a cured adhesive (suchas shown in FIG. 5), or the lens holder may be attached at the printedcircuit board by a cured adhesive (such as shown in FIG. 4). Theadhesive is initially curable in an initial radiation curing processthat comprises exposure to UV light, and the initially-cured adhesive isfurther curable to a further cured strength in a secondary thermalcuring process. The adhesive is initially cured via the initialradiation curing process after the lens is brought into focus with theimager and is optically center-aligned therewith. The initially-curedadhesive, as cured via the initial radiation curing process, holds thelens optically center-aligned and in focus with the imager. After theinitial radiation curing process, the lens holder, adhesively attachedto one of the printed circuit board and the holding element, is moved tothe secondary thermal curing process. When further cured via thesecondary thermal curing process, the further-cured adhesive maintainsfocus and optical center-alignment of the lens with the imager for useof the camera in a vehicle.

Changes and modifications in the specifically described embodiments canbe carried out without departing from the principles of the invention,which is intended to be limited only by the scope of the appendedclaims, as interpreted according to the principles of patent lawincluding the doctrine of equivalents.

1. A vehicular camera suitable for use on a vehicle, said vehicularcamera comprising: a lens comprising a plurality of optical elements;wherein said lens is disposed at a lens holder; a printed circuit board;an imager disposed at said printed circuit board; wherein one of (i)said printed circuit board is held by a holding element and said lensholder is attached at said holding element by a cured adhesive and (ii)said lens holder is attached at said printed circuit board by a curedadhesive; wherein the adhesive is initially curable in an initialradiation curing process that comprises exposure to UV light, andwherein initially-cured adhesive is further curable to a further curedstrength in a secondary thermal curing process; wherein the adhesive isinitially cured via the initial radiation curing process after said lensis brought into focus with said imager and is optically center-alignedtherewith; wherein the initially-cured adhesive, as cured via theinitial radiation curing process, holds said lens opticallycenter-aligned and in focus with said imager; wherein, after the initialradiation curing process, said lens holder, adhesively attached to oneof said printed circuit board and said holding element, is moved to thesecondary thermal curing process; wherein, when further cured via thesecondary thermal curing process, the further-cured adhesive maintainsfocus and optical center-alignment of said lens with said imager for useof said camera in a vehicle; and wherein the adhesive comprises a UVcurable and heat curable one-part filled adhesive having a viscosity at23 degrees C. from about 5,000 mPa to about 150,000 mPa and comprisingan epoxy resin.
 2. The vehicular camera of claim 1, wherein said opticalelements are disposed within a lens barrel and wherein said lens barrelis one of (i) attached at said lens holder and (ii) integral with saidlens holder.
 3. The vehicular camera of claim 1, wherein said opticalelements are disposed within a lens barrel and wherein said lens barrelone of (i) threadedly attaches at said lens holder, (ii) adhesivelyattaches at said lens holder and (iii) threadedly and adhesivelyattaches at said lens holder.
 4. The vehicular camera of claim 1,wherein said optical elements are disposed within a lens barrel andwherein said lens barrel is integrated into the lens holder such thatthey comprise a single or unitary element.
 5. The vehicular camera ofclaim 1, comprising a camera housing portion joined to said lens holder,wherein said camera housing portion and said lens holder, when joined,substantially encase said printed circuit board, and wherein said camerahousing portion comprises an electrical connector for electricallyconnecting circuitry at said printed circuit board to electrical wiringof the vehicle, and wherein said camera housing portion is joined tosaid lens holder via at least one of (i) ultrasonic welding, (ii)adhesive and (iii) press fitting.
 6. The vehicular camera of claim 1,wherein said lens holder is attached at said printed circuit board bythe cured adhesive, and wherein the further-cured adhesive maintains atleast a minimum strength of bond between the lens holder and the printedcircuit board after being exposed to at least one operating conditionfor a period of time, wherein the at least one operating conditionincludes a temperature of approximately 85 degrees Celsius, and whereinthe at least one operating condition includes a humidity ofapproximately 85%, and wherein the period of time is greater than 1000hours, and wherein the minimum strength of bond is approximately thesame as the strength of the fully cured adhesive.
 7. The vehicularcamera of claim 1, wherein at least one of (a) a lens resolution of saidlens is selected to meet but not substantially exceed a resolutiondetermined from (i) the size of a display associated with said camera,(ii) a distance between an observer and the display, (iii) a selectedpoint on a contrast sensitivity function and (iv) the size of the imagersensing surface, and (b) the lens omits achromatic lenses and employsdigital chromatic correction based on a predetermined chromaticaberration measurement.
 8. The vehicular camera of claim 1, whereinoptical center-alignment and focusing of said lens relative to saidimager is achieved robotically.
 9. The vehicular camera of claim 1,wherein the adhesive comprises one of (i) a Delo OB749 adhesive, (ii) aDelo AD VE 112203 adhesive and (iii) a Delo OB787 adhesive.
 10. Thevehicular camera of claim 1, wherein said vehicular camera is configuredfor use as a rearward viewing camera of a vehicle.
 11. A vehicularcamera suitable for use on a vehicle, said vehicular camera comprising:a lens comprising a plurality of optical elements; wherein said lens isdisposed at a lens holder; a printed circuit board; an imager disposedat said printed circuit board; a camera housing portion joined to saidlens holder, wherein said camera housing portion and said lens holder,when joined, substantially encase said printed circuit board, andwherein said camera housing portion comprises an electrical connectorfor electrically connecting circuitry at said printed circuit board toelectrical wiring of the vehicle, and wherein said camera housingportion is joined to said lens holder via at least one of (i) ultrasonicwelding, (ii) adhesive and (iii) press fitting; wherein said lens holderis attached at said printed circuit board by a cured adhesive; whereinthe adhesive is initially curable in an initial radiation curing processthat comprises exposure to UV light, and wherein initially-curedadhesive is further curable to a further cured strength in a secondarythermal curing process; wherein the adhesive is initially cured via theinitial radiation curing process after said lens is brought into focuswith said imager and is optically center-aligned therewith; wherein theinitially-cured adhesive, as cured via the initial radiation curingprocess, holds said lens optically center-aligned and in focus with saidimager; wherein, after the initial radiation curing process, said lensholder, adhesively attached to one of said printed circuit board andsaid holding element, is moved to the secondary thermal curing process;wherein, when further cured via the secondary thermal curing process,the further-cured adhesive maintains focus and optical center-alignmentof said lens with said imager for use of said camera in a vehicle;wherein the further-cured adhesive maintains at least a minimum strengthof bond between the lens holder and the printed circuit board afterbeing exposed to at least one operating condition for a period of time,wherein the at least one operating condition includes a temperature ofapproximately 85 degrees Celsius, and wherein the at least one operatingcondition includes a humidity of approximately 85%, and wherein theperiod of time is greater than 1000 hours, and wherein the minimumstrength of bond is approximately the same as the strength of the fullycured adhesive; and wherein the adhesive comprises a UV curable and heatcurable one-part filled adhesive having a viscosity at 23 degrees C.from about 5,000 mPa to about 150,000 mPa and comprising an epoxy resin.12. The vehicular camera of claim 11, wherein said optical elements aredisposed within a lens barrel and wherein said lens barrel is one of (i)attached at said lens holder and (ii) integral with said lens holder.13. The vehicular camera of claim 11, wherein said optical elements aredisposed within a lens barrel and wherein said lens barrel one of (i)threadedly attaches at said lens holder, (ii) adhesively attaches atsaid lens holder and (iii) threadedly and adhesively attaches at saidlens holder.
 14. The vehicular camera of claim 11, wherein said opticalelements are disposed within a lens barrel and wherein said lens barrelis integrated into the lens holder such that they comprise a single orunitary element.
 15. The vehicular camera of claim 11, wherein a lensresolution of said lens is selected to meet but not substantially exceeda resolution determined from (i) the size of a display associated withsaid camera, (ii) a distance between an observer and the display, (iii)a selected point on a contrast sensitivity function and (iv) the size ofthe imager sensing surface.
 16. The vehicular camera of claim 11,wherein the adhesive comprises one of (i) a Delo OB749 adhesive, (ii) aDelo AD VE 112203 adhesive and (iii) a Delo OB787 adhesive.
 17. Thevehicular camera of claim 11, wherein optical center-alignment andfocusing of said lens relative to said imager is achieved robotically.18. A vehicular camera suitable for use on a vehicle, said vehicularcamera comprising: a lens comprising a plurality of optical elements;wherein said optical elements of said lens are disposed within a lensbarrel and wherein said lens barrel is one of (i) attached at a lensholder and (ii) integral with a lens holder; a printed circuit board; animager disposed at said printed circuit board; a camera housing portionjoined to said lens holder, wherein said camera housing portion and saidlens holder, when joined, substantially encase said printed circuitboard, and wherein said camera housing portion comprises an electricalconnector for electrically connecting circuitry at said printed circuitboard to electrical wiring of the vehicle; wherein one of (i) saidprinted circuit board is held by a holding element and said lens holderis attached at said holding element by a cured adhesive and (ii) saidlens holder is attached at said printed circuit board by a curedadhesive; wherein the adhesive is initially curable in an initialradiation curing process that comprises exposure to UV light, andwherein initially-cured adhesive is further curable to a further curedstrength in a secondary thermal curing process; wherein the adhesive isinitially cured via the initial radiation curing process after said lensis brought into focus with said imager and is optically center-alignedtherewith; wherein optical center-alignment and focusing of said lensrelative to said imager is achieved robotically; wherein theinitially-cured adhesive, as cured via the initial radiation curingprocess, holds said lens optically center-aligned and in focus with saidimager; wherein, after the initial radiation curing process, said lensholder, adhesively attached to one of said printed circuit board andsaid holding element, is moved to the secondary thermal curing process;wherein, when further cured via the secondary thermal curing process,the further-cured adhesive maintains focus and optical center-alignmentof said lens with said imager for use of said camera in a vehicle; andwherein the adhesive comprises a UV curable and heat curable one-partfilled adhesive having a viscosity at 23 degrees C. from about 5,000 mPato about 150,000 mPa and comprising an epoxy resin.
 19. The vehicularcamera of claim 18, wherein the further-cured adhesive maintains atleast a minimum strength of bond strength after being exposed to atleast one operating condition for a period of time, wherein the at leastone operating condition includes a temperature of approximately 85degrees Celsius, and wherein the at least one operating conditionincludes a humidity of approximately 85%, and wherein the period of timeis greater than 1000 hours, and wherein the minimum strength of bond isapproximately the same as the strength of the fully cured adhesive. 20.The vehicular camera of claim 18, wherein at least one of (a) a lensresolution of said lens is selected to meet but not substantially exceeda resolution determined from (i) the size of a display associated withsaid camera, (ii) a distance between an observer and the display, (iii)a selected point on a contrast sensitivity function and (iv) the size ofthe imager sensing surface, and (b) the lens omits achromatic lenses andemploys digital chromatic correction based on a predetermined chromaticaberration measurement.